Superregenerative receiver



April 12, 1938- .1. 1.. REINARTZ Y ,1

I SUPERREGENERATIVE RECEIVER Filed Jan. 20, 1956 2 Sheets-Sheet i 'INVENTOR .Jo/nv Z. fiH/VARTZ JJ QQM ATTORNEY April 12, 1938..

INVENTOR JOHN L. Rfl/MRTZ ATTORNEY Patented Apr. 12, 1938 UNITED STATES SUPERREGENERATIVE RECEIVER John Ii. Reinartz, Manchester, Conn., assignor to Radio Corporation of America, a corporation of Delaware Application January 20, 1936, Serial No. 59,803

Claims. (01. 250-) The present invention relates to super-regenerative receivers and more particularly to a novel circuit arrangement utilizing a screen grid type tube for detection and for super-regeneration.

5 The theory underlying the operation of the super-regenerative type receiver is too well known at the present time to require any discussion thereof herein, however, reference may be had to U. S. Patent 1,424,065 issued July 1922 to E. H. Armstrong wherein this type of circuit is described in detail.

It is an object of the present invention to devise a circuit arrangement that readily allows super-regeneration of signals by the useof an electron stream coupled tube.

It is also an object of the present invention to devise a circuit arrangement through which it is possible to obtain the required interrupting frequency by utilizing the mush which is usually 0 present under practically all conditions of reception. Y

Other objects of the invention will be apparent from a study of the following detailed specification and the drawings.

25 I In the drawings:

Figure 1 illustrates, in diagrammatic form, a circuit arrangement embodying the present invention with an electron stream coupled tube;

Figure 2 illustrates, diagrammatically, a superregenerative receiver incorporating the invention and using a Hartley type oscillator; and,

Figure 3 is a simplified form of the circuit arrangement shown in Figure 1.

A screen grid type of tube allows the use of electron stream type of coupling to an external load without reflecting any of the load back to the control circuit. Because of this fact it is possible to use a portion-of the audio frequency variations to modulate the control grid of an oscillating electron stream coupled type of screen grid detector without the usual howling that would take place if the same connection were made with the ordinary triode tube circuit.

The present invention makes use of this possibility in a novel electron coupled super-regenerative receiverr Briefly, in such a circuit the control grid, cathode and screen grid of the tube are so connected that there is formed an oscillatory circuit which may be tuned by a suitable reactance, as for instance a condenser. In such a circuit it is well to provide a variable screen grid voltage as an aid to clearing up the received signal. The plate circuit of the tube is made through the medium of resistance coupling to the grid of an amplifier tube. According to manner of true super-regeneration with sub-fstantially perfect control over the amount of the response and without audio howl feedeback. The screen grid voltage for the screen griddetector tube may be obtained directly from the alternating component that isgenerated between the plate connection of the. amplifier tube and the screen connection of the detector tube bythe use of the coupling capacity connected between these two points.

From what has preceded, it is seen that three results are possible with the circuit arrangement of the invention. These may be briefly summarized as follows:

, 1. The relaxation or interruption frequency is generated.

q 2. The amplitude of the relaxation frequency may be controlled as well as its period; and,

3. The voltage for the screen of the detector tube may be generated thus obviating the necessity for an external voltage that would normally be required. L 1

In operating the device as above described, the coupling condenser between thev plate of the amplifier tube and the screen grid of the detector tube is adjusted to increase its capacity until heterodyne reception is possible, this takes place before the relaxation or interruption frequency generated has attained suflicient amplitude to cause super-regeneration totake place. At the same time, the voltage generated between the plate of the amplifier tube and the screen of the detector tube, provides the proper voltage for the screen causing it to react as though it had of the grid leak type and R1 is the grid leak and C2 the grid blocking condenser, while L is the tuning coiland L1 isthe section across which the tuning condenser 01 is placed, this section being connected between the cathode 2 and the ground G. Section L2 of the coil L is connected between cathode 2 and grid 4 with R1 and C2 in series. L3 is an antenna pick-up coil which may be variably coupled to the coil L. With voltage applied through R2 to grid 5 of tube T1, the circuit becomes regenerative or oscillating, determined by the value of the voltage app-lied to grid 5. While a regenerative detector circuit is very sensitive and has wide application, it is generally conceded that the super-regenerative form of detector circuit is markedly superior in sensitivity. We proceed to obtain super-regeneration in this circuit through the addition of condenser C3 which is connectedto anode 6 of tube T2. The value of condenser C3 and the combination of the values of the resistance R3 which is connected to anode I of .tube T1, the value of the blocking condenser Cs which is connected between anode l of tube T1 and grid 9 of tube T2, the value of R4v which is connected between grid 9 of tube T2 and the connection l3 of the bias battery, all help to determine, with the aid of the voltage applied to grid 5 of tube T1. if the tube circuit shall be regenerative or super-regenerative. If, with C3 set to minimum value and the value of R2 such that the circuit becomes regenerative, C1 is tuned to an incoming signal the response in the phones U will be an audio signal the frequency of .which will be determined by the extent the detector tuning differs from the incoming'frequency. If the incoming frequency were modulated, such as from a'radiophone station, the action of the regenerative detector would be to add to the reception of the modulated carrier an audio tone of a frequency determinedby the carrier frequency and the extent that the detector circuit is detuned from the carrier frequency. Only when'there is no difference frequency will the audio tone" be absent.

If the detector circuit is made super-regenerative in action, complete oscillations are prevented in the detector tubecircuit and there then can be no difference frequency or audio tone generated which would be heard along with the modulation, even though the detector circuit tuning differed in frequency from the incoming carrier frequency. In addition, the super-regenerative detectorcircuit, surpasses the regenerative detector circuit in sensitivity.

I When a relatively low-frequency alternating voltage is superimposed on the grid or anode of a regenerative detector, super-regeneration results. This low-frequency alternating voltage is usually supplied from an outside source, as from a low-frequency oscillator circuit. I

In Figure 1, use is made of the properties of the circuit connections between tube l and tube 2 to generate this low frequency and both the voltage amplitude and the frequency of this low frequency is determined by the value of condenser C3. The voltage amplitude being low when the condenser is set to a low value while the frequency is high, as the condenser value is I increased the voltage increases but the frequency decreases. By this means it is possible to arrive at a value of both voltage and frequency which gives the best result without being dependent upon an outside source for the generation of the proper low frequency and voltage amplitude. Also it is possible to go from a regenerative detector to a super-regenerative detector at'will byvarying' C3, and thus make it possible to listen to an unmodulated carrier which iskeyed or to a modulated carrier such as a radiophone' transmission, retaining the advantage of both types of reception.

In Figure 2 the same method of obtaining the relaxation or low frequency type of super-regeneration is applied to a Hartley oscillator as the function is not limited .to a certain type of circuit.

In Figure 3 the bias battery has been replaced by a cathode dropping resistor to obtain the proper value of negative bias for the amplifier tube T2.

As shown in Figures 1, 2, and 3, the antenna coupling may take on any of the usually used forms.

In actual practice it has been found that very good. results are obtained by giving the following values to the 'various component parts:

C1=100 pm, C2=100 to 250 M R1= A to 1 megohm, Ca=up to i f variable, Rz=up to 1 megohm variable, 04:.01 a), 05:.01 f, R3=%. megohm, C's=.1 ,uf, R4= A megohm.

j L1 has the turns of L in Figure 1 and Figure 2. I

It should be understood that the various embodiments described herein and the particular values for the elements of these embodiments are not to be construed as limiting the scope of the invention since obviously many modifications may be made without departing from the scope of the invention.

I claim:

1. In a receiver of the super-regenerative type, an electron stream coupled detector-oscillator tube, said tube being provided with an anode, a cathode, a signalgrid and an auxiliary grid, external circuits and means associated with the controlgrid, cathode and auxiliary grid arranged to form an oscillatory circuit, means for tuning said circuit to any frequency within a predeterminedrange of frequencies, an amplifier tube provided with an anode, a cathode and a grid, means for coupling the first named anode to the grid of the amplifier tube, means for generating the interruption frequency and impressing the generated interruption frequency upon the detector oscillator tube to thereby produce superregenerative action, said last named means including a variable condenser connected between the anode of the amplifier tube and the auxiliary grid of the first named tube and a utilizing means connected between the anode of the amplifier tube and thecathode thereof.

2. In a receiver of the super-regenerative type, an electronic tube provided with two grids, a cathode and an output electrode, means for providing signal feed .back between one of the grids and the other grid, an amplifier tube connected to the output electrode of said electronic tube, said amplifier tube beingprovided with an anode, a grid and a cathode, means for providing signal feed back between the anode of the amplifier tube and the grid thereof for generating the interrupting frequency energy and means including a variable device for impressing the interrupting frequency energy upon the electronic tube.

3. In a super-regenerative receiver, a detector oscillator circuit including an electronic tube provided with an input circuit and an output circuit, a signal energy collecting means connected to the input circuit, an amplifier tube connected to the output circuit, an interruption frequency energy generator circuit including said amplifier tube and means for impressing the generated interruption frequency energy upon the detector-oscillator circuit to thereby produce super-regenerative action, said last named means including means for conpressed upon the detector oscillator circuit, said interruption frequency energy generator circuit including a portion of the detector oscillator circuit.

4. In radio receiving apparatus of the superregenerative type, a detector-oscillator circuit .7 including an electronic tube provided with an input circuit and an output circuit, said input circuit being linked with said output circuit to facilitate the transfer of energy from said output circuit to said input circuit for producing oscillations, an amplifier circuit connected to the output circuit of said electronic tube, said amplifier circuit including a thermionic tube provided with an input circuit and an output circuit, said last named input circuit being linked with the last named output circuit to facilitate the transfer of energy from the last named output circuit to the last named input circuit for producing interruption frequency oscillations, means for controlling both the intensity and the frequency of the last named oscillations, said last named oscillationsbeing impressed upon the detector oscillator circuit so as to periodically damp the detector oscillator circuit whereby super-regenerative action is obtained.

5. In a super-regenerative receiver, a detector oscillator tube provided with an anode, a cathode and two grid electrodes, a source of space current having a negative terminal and a positive terminal, a connection between one of the gridelectrodes and the negative terminal of the source including means to give the tube detector tube characteristics and an inductance coil, a connection between the cathode of the tube and a point of said inductance coil, means for tuning said input circuit, a connection between the other grid electrode and the positive terminal of said source said connection including a variable resistor device and a condenser connected between the end of the resistor connected to the positive terminal of the source and the end of the inductance coil connected to the negative terminal of the source, a second electronic tube provided with an anode, a cathode and a control grid, a connection between the anode of the first tube and the control grid of the second tube and a coupling condenser, a connection between the anode of the first tube and said positive terminal including said resistor element and a connection between the grid of the second tube and the negative terminal of the source including a resistor element, means connecting the anode of the second tube to the second named grid. of the first tube comprising a variable condenser, a utilizing circuit connected between the anode of the second tube and the positive terminal of the source and a resistance means connected between the cathode of the second named tube and the negative terminal of the source and means for impressing the signalling energy across the first named inductance.

6. In a super-regenerative receiver, an electronic tube provided with an anode, a cathode, a screen grid and a control electrode, an input circuit for said tube and an output circuit therefor, said input circuit being provided with tuning means and means to give the tube detector tube characteristics, a source of signalling energy coupled to said input circuit, an amplifier tube pro-- vided with input and output circuits, means for electrically connecting the output of the first tube to the input of the second tube and a variable condenser connecting the anode of the second tube to thescreen grid of the first tube; i

7. Apparatus for amplifying varying" electric currents comprising an electronic tube provided with an anode, a cathode, a control grid and an auxiliary grid; aninput circuit conn'ected'between the controlgrid and the cathode of the tube, means for impressing the potential of said currents ,fupon the input circuit, a circuit con nected between the auxiliary grid and' thecath ode'of the tube, said input circuit being linked with said last named, circuit to facilitate the transfer of energy from said last named circuit to said input circuitfor producing oscillations, means for controllingthe frequency of the oscillations, an output circuitfor said tube connected between the anode of the tube and the cathode thereof, a second electronic tube provided with an anode, a cathode and a control grid, an input circuit for the second tube, means for coupling said output circuit to the input circuit of the second tube whereby energy is transferred from the first tube to the second tube, an output circuit for the second tube including a load impedance device, means for coupling the last named output circuit to the auxiliary grid including a variable reactance device, said last named coupling acting to link the output circuit of the second tube to the input thereof to facilitate the transfer of energy from the output circuit to the input circuit thereof for producing oscillations, said last named oscillations being impressed upon the first named electronic tube through said reactance to periodically stop the generation of oscillation by the first tube whereby super-regenerative action is obtained.

8. Apparatus for amplifying varying electric currents comprising an electronic tube provided with an anode, a cathode, a control grid and an auxiliary grid, an input circuit connected between the control grid and the cathode of the tube said input circuit including means to give the tube detector-tube characteristics, means for impressing the potential of said currents upon the input circuit, a circuit connected between the auxiliary grid and the cathode, said circuit including a variable resistor device, an output circuit for said tube connected between the anode and the cathode, said output circuit being linked with the input circuit to facilitate the transfer of energy from the output circuit to the input circuit for producing oscillations, a second electronic tube provided with an input circuit and an output circuit, means for coupling the last named input circuit to the output circuit of the first electronic tube whereby energy is transferred from the first tube to the second tube, a load impedance device in the output circuit of the second tube, means for coupling said last named output circuit to the auxiliary grid of the first named tube, said means includinga variable reactance device, said last named coupling means acting to link the output circuit of the second tube to the input circuit thereof to facilitate the transfer of energy from said last named output circuit to said last named input circuit for producing oscillations, said last named oscillations being impressed upon the first named electronic tube through said reactance coupling device in such a manner that the generation of oscillations of the first tube is periodically stopped whereby super-regenerative action is obtained.

9. In a receiver of electric oscillations, an electronic tube containing a cathode element, a control grid element, a screen-like anode element,

and a second anode element, an input circuit between the control grid and cathode elements, an output circuit between the screen-like anode element and the cathode element, the said circuits being coupled in such a manner as to produce regeneration, means for controlling said regeneration, a. second output circuit between the secend anode and the screen-like anode elements,

an electron tube containing a cathode element, a control grid element, a screen-like element and an anode element, said elements being inter-connected by means of external circuits, so as to provide the electron tube with an input circuit and an output circuit, said input and output circuits being coupled in such a manner as to produce oscillations, means for controlling the strength of said oscillations, a second electron tube provided with input and output circuits, and means connecting the output circuit of the first tube'to the input circuit of the second tube, and means including a variable coupling condenser for connecting the output circuit of the second tube to the output circuit of the first tube.

JOHN L. REINARTZ. 

